/* see copyright notice in trex.h */
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <setjmp.h>
#include "trex.h"

#ifdef _UINCODE
# define scisprint  iswprint
# define scstrlen   wcslen
# define scprintf   wprintf
# define _SC(x)     L(x)
#else
# define scisprint  isprint
# define scstrlen   strlen
# define scprintf   printf
# define _SC(x)     (x)
#endif


#ifdef _DEBUG
#include <stdio.h>
static const TRexChar *g_nnames[] = {
  _SC("NONE"), _SC("OP_GREEDY"), _SC("OP_OR"),
  _SC("OP_EXPR"), _SC("OP_NOCAPEXPR"), _SC("OP_DOT"), _SC("OP_CLASS"),
  _SC("OP_CCLASS"), _SC("OP_NCLASS"), _SC("OP_RANGE"), _SC("OP_CHAR"),
  _SC("OP_EOL"), _SC("OP_BOL"), _SC("OP_WB")
};
#endif


#define OP_GREEDY     (MAX_CHAR+1) // * + ? {n}
#define OP_OR         (MAX_CHAR+2)
#define OP_EXPR       (MAX_CHAR+3) //parentesis ()
#define OP_NOCAPEXPR  (MAX_CHAR+4) //parentesis (?:)
#define OP_DOT        (MAX_CHAR+5)
#define OP_CLASS      (MAX_CHAR+6)
#define OP_CCLASS     (MAX_CHAR+7)
#define OP_NCLASS     (MAX_CHAR+8) //negates class the [^
#define OP_RANGE      (MAX_CHAR+9)
#define OP_CHAR       (MAX_CHAR+10)
#define OP_EOL        (MAX_CHAR+11)
#define OP_BOL        (MAX_CHAR+12)
#define OP_WB         (MAX_CHAR+13)

#define TREX_SYMBOL_ANY_CHAR             ('.')
#define TREX_SYMBOL_GREEDY_ONE_OR_MORE   ('+')
#define TREX_SYMBOL_GREEDY_ZERO_OR_MORE  ('*')
#define TREX_SYMBOL_GREEDY_ZERO_OR_ONE   ('?')
#define TREX_SYMBOL_BRANCH               ('|')
#define TREX_SYMBOL_END_OF_STRING        ('$')
#define TREX_SYMBOL_BEGINNING_OF_STRING  ('^')
#define TREX_SYMBOL_ESCAPE_CHAR          ('\\')


typedef int TRexNodeType;

typedef struct tagTRexNode {
  TRexNodeType type;
  int left;
  int right;
  int next;
} TRexNode;

struct TRex {
  const TRexChar *_eol;
  const TRexChar *_bol;
  const TRexChar *_p;
  int _first;
  int _op;
  TRexNode *_nodes;
  int _nallocated;
  int _nsize;
  int _nsubexpr;
  TRexMatch *_matches;
  int _currsubexp;
  void *_jmpbuf;
  const TRexChar **_error;
};


static int trex_list (TRex *exp);


static int trex_newnode (TRex *exp, TRexNodeType type) {
  TRexNode n;
  int newid;
  n.type = type;
  n.next = n.right = n.left = -1;
  if (type == OP_EXPR) n.right = exp->_nsubexpr++;
  if(exp->_nallocated < (exp->_nsize+1)) {
    exp->_nallocated *= 2;
    exp->_nodes = (TRexNode *)realloc(exp->_nodes, exp->_nallocated*sizeof(TRexNode));
  }
  exp->_nodes[exp->_nsize++] = n;
  newid = exp->_nsize-1;
  return (int)newid;
}


static void trex_error (TRex *exp, const TRexChar *error) {
  if (exp->_error) *exp->_error = error;
  longjmp(*((jmp_buf*)exp->_jmpbuf), -1);
}


static void trex_expect (TRex *exp, int n){
  if ((*exp->_p) != n) trex_error(exp, _SC("expected paren"));
  exp->_p++;
}


static TRexChar trex_escapechar (TRex *exp) {
  if (*exp->_p == TREX_SYMBOL_ESCAPE_CHAR) {
    exp->_p++;
    switch (*exp->_p) {
      case 'v': exp->_p++; return '\v';
      case 'n': exp->_p++; return '\n';
      case 't': exp->_p++; return '\t';
      case 'r': exp->_p++; return '\r';
      case 'f': exp->_p++; return '\f';
      default: return (*exp->_p++);
    }
  }
  if (!scisprint(*exp->_p)) trex_error(exp, _SC("letter expected"));
  return (*exp->_p++);
}


static int trex_charclass (TRex *exp, int classid) {
  int n = trex_newnode(exp, OP_CCLASS);
  exp->_nodes[n].left = classid;
  return n;
}


static int trex_charnode (TRex *exp, TRexBool isclass) {
  TRexChar t;
  if (*exp->_p == TREX_SYMBOL_ESCAPE_CHAR) {
    exp->_p++;
    switch(*exp->_p) {
      case 'n': exp->_p++; return trex_newnode(exp, '\n');
      case 't': exp->_p++; return trex_newnode(exp, '\t');
      case 'r': exp->_p++; return trex_newnode(exp, '\r');
      case 'f': exp->_p++; return trex_newnode(exp, '\f');
      case 'v': exp->_p++; return trex_newnode(exp, '\v');
      case 'a': case 'A': case 'w': case 'W': case 's': case 'S':
      case 'd': case 'D': case 'x': case 'X': case 'c': case 'C':
      case 'p': case 'P': case 'l': case 'u': {
        t = *exp->_p; exp->_p++;
        return trex_charclass(exp, t); }
      case 'b':
      case 'B':
        if (!isclass) {
          int node = trex_newnode(exp, OP_WB);
          exp->_nodes[node].left = *exp->_p;
          exp->_p++;
          return node;
        } //else default
      default:
        t = *exp->_p; exp->_p++;
        return trex_newnode(exp, t);
    }
  }
  else if (!scisprint(*exp->_p)) trex_error(exp, _SC("letter expected"));
  t = *exp->_p; exp->_p++;
  return trex_newnode(exp, t);
}


static int trex_class (TRex *exp) {
  int ret = -1;
  int first = -1, chain;
  if (*exp->_p == TREX_SYMBOL_BEGINNING_OF_STRING) {
    ret = trex_newnode(exp, OP_NCLASS);
    exp->_p++;
  } else ret = trex_newnode(exp, OP_CLASS);
  if (*exp->_p == ']') trex_error(exp, _SC("empty class"));
  chain = ret;
  while (*exp->_p != ']' && exp->_p != exp->_eol) {
    if (*exp->_p == '-' && first != -1){
      int r, t;
      if(*exp->_p++ == ']') trex_error(exp, _SC("unfinished range"));
      r = trex_newnode(exp, OP_RANGE);
      if(first>*exp->_p) trex_error(exp, _SC("invalid range"));
      if(exp->_nodes[first].type == OP_CCLASS) trex_error(exp, _SC("cannot use character classes in ranges"));
      exp->_nodes[r].left = exp->_nodes[first].type;
      t = trex_escapechar(exp);
      exp->_nodes[r].right = t;
      exp->_nodes[chain].next = r;
      chain = r;
      first = -1;
    } else {
      if (first!=-1){
        int c = first;
        exp->_nodes[chain].next = c;
        chain = c;
        first = trex_charnode(exp, TRex_True);
      } else {
        first = trex_charnode(exp, TRex_True);
      }
    }
  }
  if (first!=-1) {
    int c = first;
    exp->_nodes[chain].next = c;
    chain = c;
    first = -1;
  }
  /* hack? */
  exp->_nodes[ret].left = exp->_nodes[ret].next;
  exp->_nodes[ret].next = -1;
  return ret;
}


static int trex_parsenumber (TRex *exp) {
  int ret = *exp->_p-'0';
  int positions = 10;
  exp->_p++;
  while (isdigit(*exp->_p)) {
    ret = ret*10+(*exp->_p++-'0');
    if (positions==1000000000) trex_error(exp, _SC("overflow in numeric constant"));
    positions *= 10;
  }
  return ret;
}


static int trex_element (TRex *exp) {
  int ret = -1;
  switch (*exp->_p) {
    case '(': {
      int expr, newn;
      exp->_p++;
      if (*exp->_p =='?') {
        exp->_p++;
        trex_expect(exp, ':');
        expr = trex_newnode(exp, OP_NOCAPEXPR);
      } else {
        expr = trex_newnode(exp, OP_EXPR);
      }
      newn = trex_list(exp);
      exp->_nodes[expr].left = newn;
      ret = expr;
      trex_expect(exp, ')');
      break;
      }
    case '[':
      exp->_p++;
      ret = trex_class(exp);
      trex_expect(exp, ']');
      break;
    case TREX_SYMBOL_END_OF_STRING: exp->_p++; ret = trex_newnode(exp, OP_EOL);break;
    case TREX_SYMBOL_ANY_CHAR: exp->_p++; ret = trex_newnode(exp, OP_DOT);break;
    default:
      ret = trex_charnode(exp, TRex_False);
      break;
  }
  {
    int op;
    TRexBool isgreedy = TRex_False;
    unsigned short p0 = 0, p1 = 0;
    switch (*exp->_p) {
      case TREX_SYMBOL_GREEDY_ZERO_OR_MORE: p0 = 0; p1 = 0xFFFF; exp->_p++; isgreedy = TRex_True; break;
      case TREX_SYMBOL_GREEDY_ONE_OR_MORE: p0 = 1; p1 = 0xFFFF; exp->_p++; isgreedy = TRex_True; break;
      case TREX_SYMBOL_GREEDY_ZERO_OR_ONE: p0 = 0; p1 = 1; exp->_p++; isgreedy = TRex_True; break;
      case '{':
        exp->_p++;
        if (!isdigit(*exp->_p)) trex_error(exp, _SC("number expected"));
        p0 = (unsigned short)trex_parsenumber(exp);
        /*******************************/
        switch (*exp->_p) {
          case '}': p1 = p0; exp->_p++; break;
          case ',':
            exp->_p++;
            p1 = 0xFFFF;
            if (isdigit(*exp->_p)) p1 = (unsigned short)trex_parsenumber(exp);
            trex_expect(exp, '}');
            break;
          default:
            trex_error(exp, _SC(", or } expected"));
        }
        /*******************************/
        isgreedy = TRex_True;
        break;
    }
    if (isgreedy) {
      int nnode = trex_newnode(exp, OP_GREEDY);
      op = OP_GREEDY;
      exp->_nodes[nnode].left = ret;
      exp->_nodes[nnode].right = ((p0)<<16)|p1;
      ret = nnode;
    }
  }
  if ((*exp->_p != TREX_SYMBOL_BRANCH) && (*exp->_p != ')') &&
      (*exp->_p != TREX_SYMBOL_GREEDY_ZERO_OR_MORE) &&
      (*exp->_p != TREX_SYMBOL_GREEDY_ONE_OR_MORE) &&
      (*exp->_p != '\0')) {
    int nnode = trex_element(exp);
    exp->_nodes[ret].next = nnode;
  }
  return ret;
}


static int trex_list (TRex *exp) {
  int ret = -1, e;
  if (*exp->_p == TREX_SYMBOL_BEGINNING_OF_STRING) {
    exp->_p++;
    ret = trex_newnode(exp, OP_BOL);
  }
  e = trex_element(exp);
  if (ret != -1) exp->_nodes[ret].next = e; else ret = e;
  if (*exp->_p == TREX_SYMBOL_BRANCH) {
    int temp, tright;
    exp->_p++;
    temp = trex_newnode(exp, OP_OR);
    exp->_nodes[temp].left = ret;
    tright = trex_list(exp);
    exp->_nodes[temp].right = tright;
    ret = temp;
  }
  return ret;
}


static TRexBool trex_matchcclass (int cclass, TRexChar c) {
  switch (cclass) {
    case 'a': return isalpha(c)?TRex_True:TRex_False;
    case 'A': return !isalpha(c)?TRex_True:TRex_False;
    case 'w': return (isalnum(c) || c == '_')?TRex_True:TRex_False;
    case 'W': return (!isalnum(c) && c != '_')?TRex_True:TRex_False;
    case 's': return isspace(c)?TRex_True:TRex_False;
    case 'S': return !isspace(c)?TRex_True:TRex_False;
    case 'd': return isdigit(c)?TRex_True:TRex_False;
    case 'D': return !isdigit(c)?TRex_True:TRex_False;
    case 'x': return isxdigit(c)?TRex_True:TRex_False;
    case 'X': return !isxdigit(c)?TRex_True:TRex_False;
    case 'c': return iscntrl(c)?TRex_True:TRex_False;
    case 'C': return !iscntrl(c)?TRex_True:TRex_False;
    case 'p': return ispunct(c)?TRex_True:TRex_False;
    case 'P': return !ispunct(c)?TRex_True:TRex_False;
    case 'l': return islower(c)?TRex_True:TRex_False;
    case 'u': return isupper(c)?TRex_True:TRex_False;
  }
  return TRex_False; /*cannot happen*/
}


static TRexBool trex_matchclass (TRex* exp, TRexNode *node, TRexChar c) {
  do {
    switch (node->type) {
      case OP_RANGE:
        if (c >= node->left && c <= node->right) return TRex_True;
        break;
      case OP_CCLASS:
        if (trex_matchcclass(node->left, c)) return TRex_True;
        break;
      default:
        if (c == node->type)return TRex_True;
    }
  } while ((node->next != -1) && (node = &exp->_nodes[node->next]));
  return TRex_False;
}


static const TRexChar *trex_matchnode (TRex* exp, TRexNode *node, const TRexChar *str, TRexNode *next) {
  TRexNodeType type = node->type;
  switch (type) {
    case OP_GREEDY: {
      //TRexNode *greedystop = (node->next != -1) ? &exp->_nodes[node->next] : NULL;
      TRexNode *greedystop = NULL;
      int p0 = (node->right >> 16)&0x0000FFFF, p1 = node->right&0x0000FFFF, nmaches = 0;
      const TRexChar *s=str, *good = str;
      if (node->next != -1) greedystop = &exp->_nodes[node->next]; else greedystop = next;
      while ((nmaches == 0xFFFF || nmaches < p1)) {
        const TRexChar *stop;
        if (!(s = trex_matchnode(exp, &exp->_nodes[node->left], s, greedystop))) break;
        nmaches++;
        good = s;
        if (greedystop) {
          //checks that 0 matches satisfy the expression(if so skips)
          //if not would always stop(for instance if is a '?')
          if (greedystop->type != OP_GREEDY ||
              (greedystop->type == OP_GREEDY && ((greedystop->right >> 16)&0x0000FFFF) != 0)) {
            TRexNode *gnext = NULL;
            if (greedystop->next != -1) gnext = &exp->_nodes[greedystop->next];
            else if (next && next->next != -1) gnext = &exp->_nodes[next->next];
            stop = trex_matchnode(exp, greedystop, s, gnext);
            if (stop) {
              //if satisfied stop it
              if (p0 == p1 && p0 == nmaches) break;
              else if (nmaches >= p0 && p1 == 0xFFFF) break;
              else if (nmaches >= p0 && nmaches <= p1) break;
            }
          }
        }
        if (s >= exp->_eol) break;
      }
      if (p0 == p1 && p0 == nmaches) return good;
      if (nmaches >= p0 && p1 == 0xFFFF) return good;
      if (nmaches >= p0 && nmaches <= p1) return good;
      return NULL;
      }
    case OP_OR: {
      const TRexChar *asd = str;
      TRexNode *temp=&exp->_nodes[node->left];
      while ((asd = trex_matchnode(exp, temp, asd, NULL))) {
        if (temp->next != -1) temp = &exp->_nodes[temp->next]; else return asd;
      }
      asd = str;
      temp = &exp->_nodes[node->right];
      while ((asd = trex_matchnode(exp, temp, asd, NULL))) {
        if (temp->next != -1) temp = &exp->_nodes[temp->next]; else return asd;
      }
      return NULL;
      }
    case OP_EXPR:
    case OP_NOCAPEXPR: {
      TRexNode *n = &exp->_nodes[node->left];
      const TRexChar *cur = str;
      int capture = -1;
      if (node->type != OP_NOCAPEXPR && node->right == exp->_currsubexp) {
        capture = exp->_currsubexp;
        exp->_matches[capture].begin = cur;
        exp->_currsubexp++;
      }
      do {
        TRexNode *subnext = NULL;
        if (n->next != -1) subnext = &exp->_nodes[n->next]; else subnext = next;
        if (!(cur = trex_matchnode(exp, n, cur, subnext))) {
          if (capture != -1){
            exp->_matches[capture].begin = 0;
            exp->_matches[capture].len = 0;
          }
          return NULL;
        }
      } while ((n->next != -1) && (n = &exp->_nodes[n->next]));
      if (capture != -1) exp->_matches[capture].len = cur-exp->_matches[capture].begin;
      return cur;
      }
    case OP_WB:
      if ((str == exp->_bol && !isspace(*str)) ||
          (str == exp->_eol && !isspace(*(str-1))) ||
          (!isspace(*str) && isspace(*(str+1))) ||
          (isspace(*str) && !isspace(*(str+1)))) return node->left=='b' ? str : NULL;
      return node->left=='b' ? NULL : str;
    case OP_BOL:
      if (str == exp->_bol) return str;
      return NULL;
    case OP_EOL:
      if (str == exp->_eol) return str;
      return NULL;
    case OP_DOT:
      str++;
      return str;
    case OP_NCLASS:
    case OP_CLASS:
      if (trex_matchclass(exp, &exp->_nodes[node->left], *str) ?
            (type == OP_CLASS ? TRex_True : TRex_False) :
            (type == OP_NCLASS ? TRex_True : TRex_False)) {
        str++;
        return str;
      }
      return NULL;
    case OP_CCLASS:
      if (trex_matchcclass(node->left, *str)) {
        str++;
        return str;
      }
      return NULL;
    default: /* char */
      if (*str != node->type) return NULL;
      str++; /* *str++; */
      return str;
  }
  return NULL;
}


/* public api */
TRex *trex_compile (const TRexChar *pattern, const TRexChar **error) {
  TRex *exp = (TRex *)malloc(sizeof(TRex));
  exp->_eol = exp->_bol = NULL;
  exp->_p = pattern;
  exp->_nallocated = (int)scstrlen(pattern)*sizeof(TRexChar);
  exp->_nodes = (TRexNode *)malloc(exp->_nallocated*sizeof(TRexNode));
  exp->_nsize = 0;
  exp->_matches = 0;
  exp->_nsubexpr = 0;
  exp->_first = trex_newnode(exp, OP_EXPR);
  exp->_error = error;
  exp->_jmpbuf = malloc(sizeof(jmp_buf));
  if (setjmp(*((jmp_buf *)exp->_jmpbuf)) == 0) {
    int res = trex_list(exp);
    exp->_nodes[exp->_first].left = res;
    if (*exp->_p!='\0') trex_error(exp, _SC("unexpected character"));
#ifdef _DEBUG
    {
      int nsize, i;
      TRexNode *t;
      nsize = exp->_nsize;
      t = &exp->_nodes[0];
      scprintf(_SC("\n"));
      for (i = 0;i < nsize; i++) {
        if(exp->_nodes[i].type > MAX_CHAR)
          scprintf(_SC("[%02d] %10s "), i, g_nnames[exp->_nodes[i].type-MAX_CHAR]);
        else
          scprintf(_SC("[%02d] %10c "), i, exp->_nodes[i].type);
        scprintf(_SC("left %02d right %02d next %02d\n"), exp->_nodes[i].left, exp->_nodes[i].right, exp->_nodes[i].next);
      }
      scprintf(_SC("\n"));
    }
#endif
    exp->_matches = (TRexMatch *)malloc(exp->_nsubexpr*sizeof(TRexMatch));
    memset(exp->_matches, 0, exp->_nsubexpr*sizeof(TRexMatch));
  } else {
    trex_free(exp);
    return NULL;
  }
  return exp;
}


void trex_free (TRex *exp) {
  if (exp) {
    if (exp->_nodes) free(exp->_nodes);
    if (exp->_jmpbuf) free(exp->_jmpbuf);
    if (exp->_matches) free(exp->_matches);
    free(exp);
  }
}


TRexBool trex_match (TRex *exp, const TRexChar *text) {
  const TRexChar *res = NULL;
  exp->_bol = text;
  exp->_eol = text+scstrlen(text);
  exp->_currsubexp = 0;
  res = trex_matchnode(exp, exp->_nodes, text, NULL);
  if (res == NULL || res != exp->_eol) return TRex_False;
  return TRex_True;
}


TRexBool trex_searchrange (TRex *exp, const TRexChar *text_begin, const TRexChar *text_end,
  const TRexChar **out_begin, const TRexChar **out_end)
{
  const TRexChar *cur = NULL;
  int node = exp->_first;
  if (text_begin >= text_end) return TRex_False;
  exp->_bol = text_begin;
  exp->_eol = text_end;
  do {
    cur = text_begin;
    while (node != -1) {
      exp->_currsubexp = 0;
      cur = trex_matchnode(exp, &exp->_nodes[node], cur, NULL);
      if (!cur) break;
      node = exp->_nodes[node].next;
    }
    text_begin++;
  } while (cur == NULL && text_begin != text_end);
  if (cur == NULL) return TRex_False;
  --text_begin;
  if (out_begin) *out_begin = text_begin;
  if (out_end) *out_end = cur;
  return TRex_True;
}


TRexBool trex_search (TRex *exp, const TRexChar *text, const TRexChar **out_begin, const TRexChar **out_end) {
  return trex_searchrange(exp, text, text+scstrlen(text), out_begin, out_end);
}


int trex_getsubexpcount (TRex *exp) {
  return exp->_nsubexpr;
}


TRexBool trex_getsubexp (TRex *exp, int n, TRexMatch *subexp) {
  if (n < 0 || n >= exp->_nsubexpr) return TRex_False;
  *subexp = exp->_matches[n];
  return TRex_True;
}
